The goal of plant breeding is to combine various desirable traits in a single variety or hybrid. Such desirable traits may include greater yield, resistance to diseases, insects or other pests, tolerance to heat and drought, better agronomic quality, higher nutritional value, enhanced growth rate and improved fruit properties.
Breeding techniques take advantage of a plant's method of pollination. There are two general methods of pollination: a plant self-pollinates if pollen from one flower is transferred to the same or another flower of the same genotype. A plant cross-pollinates if pollen comes to it from a flower of a different genotype.
Plants that have been self-pollinated and selected for (uniform) type over many generations become homozygous at almost all gene loci and produce a uniform population of true breeding progeny of homozygous plants. A cross between two such homozygous plants of different lines produces a uniform population of hybrid plants that are heterozygous for many gene loci. The extent of heterozygosity in the hybrid is a function of the genetic distance between the parents. Conversely, a cross of two plants each heterozygous at a number of loci produces a segregating population of hybrid plants that differ genetically and are not uniform. The resulting non-uniformity makes performance unpredictable.
The development of uniform varieties requires the development of homozygous inbred plants, the crossing of these inbred plants to make hybrids, and the evaluation of the hybrids resulting from the crosses. Pedigree breeding and recurrent selection are examples of breeding methods that have been used to develop inbred plants from breeding populations. Those breeding methods combine the genetic backgrounds from two or more plants or various other broad-based sources into breeding pools from which new lines are developed by selfing and selection of desired phenotypes. The new plants are evaluated to determine which have commercial potential.
Spinach (Spinacia oleracea) is a flowering plant in the family Amaranthaceae. Spinach is an annual plant (rarely biennial) having flowers that mature into a small hard dry lumpy fruit cluster about 5-10 mm across containing several seeds.
Spinach has two stages in its life cycle including the vegetative, rosette stage in which the plant is marketable (about 35-40 days) and the bolting, seed stalk stage in which the plant is no longer marketable. Spinach can grow in a range of soils as long as they are moist and fertile, and particularly sandy loams that are high in organic matter.
While breeding efforts to date have provided a number of useful spinach lines with beneficial traits, there remains a great need in the art for new varieties with further improved traits. Such plants would benefit farmers and consumers alike by improving crop yields and/or quality. Some breeding objectives include varying the color, and texture of the leaf. Other objectives include disease or pest resistance, yield, suitability to various climatic circumstances, earliness, and fast growth.